Method of treating cancer based on identifying mutations in the extracellular domain III of epidermal growth factor receptor gene

The invention relates to new identified mutations in the epidermal growth factor receptor gene, leading to amino acidic changes which highly correlate with the resistance to a therapy regimen comprising cetuximab. The invention includes peptide sequences and primers to detect the mutations, as well as kits for predicting the response of a subject to a therapy regime comprising cetuximab. In particular, the invention is useful in the therapy regimen applicable to metastasic colorectal cancer.